Battery voltage question (again)
Road Master
Joined: Jan 2010
Posts: 881
Likes: 13
From: ONT
A fully charged battery should show a charge of 13.8 Volts. Even when shut-off H-D bikes have a drain on them. Security System and Harmon Kardon radio to name but a few.
Extreme HDF Member
Joined: Sep 2010
Posts: 14,744
Likes: 402
From: Phoenix '53, '88, '09 Big Twins
the stator output is rpm dependent and is in measured is AC volts- the old spec was 16 to 20 VAC per 1000 RPMs
the battery not only stores energy but is used to help regulate "spikes" from affecting the bike's systems so that voltage is not jumping from 14.8 volts to 10 volts if shifting gears for example...when rpm changes instantaneously.
these are all vehicle electrics basics and unchanged - the only real change is the switch from DC generators to alternators in the late 60's.
as pointed out above ( and many times) the in dash voltmeter is not an accurate indicator of charging system operation, it is subject to voltage drop in the wiring harness and affected by the other loads, such as lights, horn etc.
diagnostic measurements are taken at the battery.
The OP's observations are "normal"
...a bike idling at 1000 rpms may put out 16 volts AC, some of that is lost when the waves are chopped into DC by the regulator...and the bike's electrics area load, lights, radio, fuel pump...all that stuff so to see 12 VDC more or less is normal
mike
Last edited by mkguitar; Jun 2, 2014 at 01:56 PM.
Extreme HDF Member
Joined: Sep 2010
Posts: 14,744
Likes: 402
From: Phoenix '53, '88, '09 Big Twins
please refer to this chart:
www.mmbalmainauto.com.au/PDF/State_of_charge_12_volt_batteries.pdf
if you have questions about the source, a quick google will show this chart to be universal and accepted figures
12.7 volts shows a 100% charged battery
www.mmbalmainauto.com.au/PDF/State_of_charge_12_volt_batteries.pdf
if you have questions about the source, a quick google will show this chart to be universal and accepted figures
12.7 volts shows a 100% charged battery
Last edited by mkguitar; Jun 2, 2014 at 12:52 PM.
Road Master
Joined: Dec 2009
Posts: 843
Likes: 43
From: Louisiana
Last time I posted a question most of the respondents went off in a tangent and nobody really answer my question. Let's try it again.The question is:
When I am actuating the throttle (giving it gas) the Voltage gauge on the fairing shows 14V but when I let go the throttle it drops to about 12.7 V. I put a volt meter on the battery and the battery shows the same voltage as the gauge on the fairing. So is this normal?
I am worried it may be the regulator starting to go. The dealer says it is but I do not trust them 100%. BTW, I did put a new battery and it does the same thing
When I am actuating the throttle (giving it gas) the Voltage gauge on the fairing shows 14V but when I let go the throttle it drops to about 12.7 V. I put a volt meter on the battery and the battery shows the same voltage as the gauge on the fairing. So is this normal?
I am worried it may be the regulator starting to go. The dealer says it is but I do not trust them 100%. BTW, I did put a new battery and it does the same thing
Road Master
Joined: Sep 2006
Posts: 793
Likes: 23
From: AZ
Most charts show voltage at 12.6 Volts State of Charge is 100% If your battery at Idle shows 12.7 I would say the battery is ok. If you follow the directions in the Maintenance Manual, testing the Stater and the Regulator is not that hard to do. To give you a more direct answer then yes, its normal, I am only stating this as mine does the same as your question refers to.
Thread Starter
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Tourer
Joined: Aug 2008
Posts: 493
Likes: 17
From: Ft LAuderdale
Guess what guys. Most of you AND my mechanic are right. Called the Harley factory
and talked to an "expert" , he said it is normal. Thanks so much. I thought I had an excuse to buy a 2014. Oh well
and talked to an "expert" , he said it is normal. Thanks so much. I thought I had an excuse to buy a 2014. Oh well
Road Master
Joined: Dec 2009
Posts: 843
Likes: 43
From: Louisiana
That's weird. So it's normal for a Harley not to put out enough voltage at idle to charge the battery? Sorry but that's just bullshit. I've never seen a charging system on a bike, car, truck or even a aircraft that didn't put out voltage above battery voltage at idle. My RG puts out between 14.1 to 14.3 volts all the time. I'm not saying all bikes will act exactly the same as mine. Harley's service manual doesn't even give a specification for voltage output at idle so it's not hard to understand that if it meets the voltage at higher rpms like yours does they'd say your good. Go put a volt meter on your car battery at idle, heck if you've got a riding mower do the same. Then come back and tell me if you still think your Harley is acting normal.
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Extreme HDF Member
Joined: Sep 2010
Posts: 14,744
Likes: 402
From: Phoenix '53, '88, '09 Big Twins
again- at abut 1000 rpms +/- 50 ( idle speed) the stator will output about 16 to 23 volts AC. ( source 2009 service manual table 7.2, the previous spec was 16 ~20 for Evos and early twin cams)
that AC is rectified to DC by diodes- this is done with a diode bridge which essentially chops the tops/ bottoms off the AC current sine wave..resulting is a straight line DC voltage.
this process sacrifices voltage..converted to heat ( and voltage will be limited to under 14.8 DC.. shed as heat)
The net voltage to the battery will be less than the 16~23 volts the stator was producing at the 1000 rpm idle speed.
the battery is a reservoir and will provide power for all the lights, fuel pump, radio, ecm etc
but the idling bike will be about 12 volts-ish depending how much stuff is running...honk your horn, you'll see the meter jump down, hit you spots and high beam, the meter will go down
the battery will also condition the electrical system from spikes which may occur if the rpms change rapidly
mike
Last edited by mkguitar; Jun 2, 2014 at 05:28 PM.
Road Master
Joined: Dec 2009
Posts: 843
Likes: 43
From: Louisiana
no it is normal.
again- at abut 1000 rpms +/- 50 ( idle speed) the stator will output about 16 to 23 volts AC. ( source 2009 service manual table 7.2, the previous spec was 16 ~20 for Evos and early twin cams)
that AC is rectified to DC by diodes- this is done with a diode bridge which essentially chops the tops/ bottoms off the AC current sine wave..resulting is a straight line DC voltage.
this process sacrifices voltage..converted to heat ( and voltage will be limited to under 14.8 DC.. shed as heat)
The net voltage to the battery will be less than the 16~23 volts the stator was producing at the 1000 rpm idle speed.
the battery is a reservoir and will provide power for all the lights, fuel pump, radio, ecm etc
but the idling bike will be about 12 volts-ish depending how much stuff is running...honk your horn, you'll see the meter jump down, hit you spots and high beam, the meter will go down
the battery will also condition the electrical system from spikes which may occur if the rpms change rapidly
mike
again- at abut 1000 rpms +/- 50 ( idle speed) the stator will output about 16 to 23 volts AC. ( source 2009 service manual table 7.2, the previous spec was 16 ~20 for Evos and early twin cams)
that AC is rectified to DC by diodes- this is done with a diode bridge which essentially chops the tops/ bottoms off the AC current sine wave..resulting is a straight line DC voltage.
this process sacrifices voltage..converted to heat ( and voltage will be limited to under 14.8 DC.. shed as heat)
The net voltage to the battery will be less than the 16~23 volts the stator was producing at the 1000 rpm idle speed.
the battery is a reservoir and will provide power for all the lights, fuel pump, radio, ecm etc
but the idling bike will be about 12 volts-ish depending how much stuff is running...honk your horn, you'll see the meter jump down, hit you spots and high beam, the meter will go down
the battery will also condition the electrical system from spikes which may occur if the rpms change rapidly
mike